scholarly journals Natural heterogeneity of α2-antiplasmin: functional and clinical consequences

Blood ◽  
2016 ◽  
Vol 127 (5) ◽  
pp. 538-545 ◽  
Author(s):  
Shiraazkhan Abdul ◽  
Frank W. G. Leebeek ◽  
Dingeman C. Rijken ◽  
Shirley Uitte de Willige
Keyword(s):  
Fibrin Clot ◽  
Clot Lysis ◽  
Thrombotic Risk ◽  
Amino Terminal ◽  
Inhibitory Function ◽  
C Terminus ◽  
N Terminus ◽  
Clinical Consequences ◽  
Carboxyl Terminal ◽  
Plasmin Inhibitor

AbstractHuman α2-antiplasmin (α2AP, also called α2-plasmin inhibitor) is the main physiological inhibitor of the fibrinolytic enzyme plasmin. α2AP inhibits plasmin on the fibrin clot or in the circulation by forming plasmin-antiplasmin complexes. Severely reduced α2AP levels in hereditary α2AP deficiency may lead to bleeding symptoms, whereas increased α2AP levels have been associated with increased thrombotic risk. α2AP is a very heterogeneous protein. In the circulation, α2AP undergoes both amino terminal (N-terminal) and carboxyl terminal (C-terminal) proteolytic modifications that significantly modify its activities. About 70% of α2AP is cleaved at the N terminus by antiplasmin-cleaving enzyme (or soluble fibroblast activation protein), resulting in a 12-amino-acid residue shorter form. The glutamine residue that serves as a substrate for activated factor XIII becomes more efficient after removal of the N terminus, leading to faster crosslinking of α2AP to fibrin and consequently prolonged clot lysis. In approximately 35% of circulating α2AP, the C terminus is absent. This C terminus contains the binding site for plasmin(ogen), the key component necessary for the rapid and efficient inhibitory mechanism of α2AP. Without its C terminus, α2AP can no longer bind to the lysine binding sites of plasmin(ogen) and is only a kinetically slow plasmin inhibitor. Thus, proteolytic modifications of the N and C termini of α2AP constitute major regulatory mechanisms for the inhibitory function of the protein and may therefore have clinical consequences. This review presents recent findings regarding the main aspects of the natural heterogeneity of α2AP with particular focus on the functional and possible clinical implications.

A fusion protein with improved thrombolytic effect and low bleeding risk

2009 ◽  
Vol 102 (12) ◽  
pp. 1194-1203 ◽  
Author(s):  
Lisheng Wang ◽  
Qinglin Zhang ◽  
Yide Qin ◽  
Chutse Wu ◽  
Xiudong Wang ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Anticoagulant Activity ◽  
Bleeding Risk ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Recognition Sequence ◽  
Linker Peptide ◽  
C Terminus ◽  
N Terminus

SummaryTo resolve the therapeutic dilemma between efficacy of thrombolysis and bleeding risk associated with the use of a combination of thrombolytic and anticoagulant treatments, we created a fusion protein. Staphylokinase was fused to the N-terminus of hirudin using thrombin recognition sequence as linker peptide, resulting in a fusion protein STH.We hypothesised that STH would be cleaved by thrombin at the thrombus site, releasing staphylokinase and hirudin to perform bifunctionally, and attenuating bleeding risk. SDS-PAGE andWestern blot analyses indicated that the linker peptide could be specially recognised and cleaved by thrombin. Amidolytic and thromboelastogram assays showed that the N-terminus of hirudin in STH was blocked by staphylokinase and linker peptide, impeding hirudin’s anticoagulant activity. Once cleaved, STH displayed 35.7% of the anticoagulant activity of equimolar hirudin and exhibited anticoagulant effects in the fibrin clot lysis assay.Thrombin-binding and fibrin clot lysis assays showed that the C-terminus of hirudin retained its high affinity for thrombin. Moreover, STH showed improved thrombolytic effects and a lower bleeding risk in animals. Thus, STH may have the capacity to perform bifunctionally and release anticoagulant activity in a thrombus-targeted manner in vivo, which may reduce the bleeding risk that often accompanies high thrombolytic efficacy in the treatment of thromboembolic diseases.

scholarly journals Incorporation of α2-Plasmin Inhibitor into Fibrin Clots and Its Association with the Clinical Outcome of Acute Ischemic Stroke Patients

Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 347
Author(s):  
Zsuzsa Bagoly ◽  
Barbara Baráth ◽  
Rita Orbán-Kálmándi ◽  
István Szegedi ◽  
Réka Bogáti ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Intracranial Hemorrhage ◽  
Intravenous Thrombolysis ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Stroke Patients ◽  
Plasmin Inhibitor ◽  
Fibrin Clots

Cross-linking of α2-plasmin inhibitor (α2-PI) to fibrin by activated factor XIII (FXIIIa) is essential for the inhibition of fibrinolysis. Little is known about the factors modifying α2-PI incorporation into the fibrin clot and whether the extent of incorporation has clinical consequences. Herein we calculated the extent of α2-PI incorporation by measuring α2-PI antigen levels from plasma and serum obtained after clotting the plasma by thrombin and Ca2+. The modifying effect of FXIII was studied by spiking of FXIII-A-deficient plasma with purified plasma FXIII. Fibrinogen, FXIII, α2-PI incorporation, in vitro clot-lysis, soluble fibroblast activation protein and α2-PI p.Arg6Trp polymorphism were measured from samples of 57 acute ischemic stroke patients obtained before thrombolysis and of 26 healthy controls. Increasing FXIII levels even at levels above the upper limit of normal increased α2-PI incorporation into the fibrin clot. α2-PI incorporation of controls and patients with good outcomes did not differ significantly (49.4 ± 4.6% vs. 47.4 ± 6.7%, p = 1.000), however it was significantly lower in patients suffering post-lysis intracranial hemorrhage (37.3 ± 14.0%, p = 0.004). In conclusion, increased FXIII levels resulted in elevated incorporation of α2-PI into fibrin clots. In stroke patients undergoing intravenous thrombolysis treatment, α2-PI incorporation shows an association with the outcome of therapy, particularly with thrombolysis-associated intracranial hemorrhage.

scholarly journals Anabolic–Androgenic Steroid Abuse Impairs Fibrin Clot Lysis

2020 ◽  
Author(s):  
Johannes Jakobsen Sidelmann ◽  
Jørgen Brodersen Gram ◽  
Jon J. Rasmussen ◽  
Caroline Kistorp
Keyword(s):  
Plasma Concentrations ◽  
Coagulation Factor ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Cross Sectional ◽  
Plasmin Inhibitor ◽  
Pai 1 ◽  
Fibrin Structure ◽  
Structure Properties

AbstractAbuse of anabolic–androgenic steroids (AASs) is suspected to increase the risk of cardiovascular disease (CVD) and cardiovascular mortality in otherwise healthy individuals. AAS abuse may increase the incidence of CVD by altering the hemostatic balance toward a procoagulant state. Studies on the effect of AAS abuse on the fibrinolytic system, however, have either demonstrated a profibrinolytic effect or no effect of AAS abuse, but the overall effect of AAS on fibrinolysis has not been addressed so far. This cross-sectional study investigated the effect of AAS on fibrin clot lysis, fibrin structure, and the hemostatic proteins, potentially affecting these measures in current and former AAS abusers and healthy age-matched controls. The study population consisted of 37 current and 33 former AAS abusers, along with 30 healthy age-matched controls. Fibrin clot lysis, fibrin structure properties, fibrinogen, coagulation factor XIII (FXIII) plasminogen, plasmin inhibitor, plasminogen activator inhibitor-1 (PAI-1), and thrombin activatable fibrinolysis inhibitor (TAFI) were determined. Fibrin clot lysis was significantly reduced in participants abusing AAS compared with former abusers and controls (p < 0.001). Plasma fibrinogen, plasminogen, and plasmin inhibitor were significantly increased in current abusers (p < 0.05). No significant differences were observed with respect to measures of fibrin structure properties, PAI-1, and TAFI (p > 0.05). In conclusion, AAS abuse depresses fibrin clot lysis. This effect is not associated with alterations in fibrin structure but is rather caused by increased plasma concentrations of fibrinogen, FXIII, and plasmin inhibitor. These findings suggest that AAS abuse may be associated with increased thrombotic disease.

A novel plasma proteinase potentiates α2-antiplasmin inhibition of fibrin digestion

Blood ◽  
2004 ◽  
Vol 103 (10) ◽  
pp. 3783-3788 ◽  
Author(s):  
Kyung N. Lee ◽  
Kenneth W. Jackson ◽  
Victoria J. Christiansen ◽  
Keun H. Chung ◽  
Patrick A. McKee
Keyword(s):  
Human Plasma ◽  
Catalytic Properties ◽  
Fibroblast Activation Protein ◽  
Clot Lysis ◽  
Direct Proportion ◽  
N Terminus ◽  
Rapid Removal ◽  
Membrane Bound ◽  
Plasmin Inhibitor ◽  
Pharmacologic Inhibition

Abstract Human α2-antiplasmin (α2AP), also known as α2-plasmin inhibitor, is the major inhibitor of the proteolytic enzyme plasmin that digests fibrin. There are 2 N-terminal forms of α2AP that circulate in human plasma: a 464-residue protein with Met as the N-terminus, Met-α2AP, and a 452-residue version with Asn as the N-terminus, Asn-α2AP. We have discovered and purified a proteinase from human plasma that cleaves the Pro12-Asn13 bond of Met-α2AP to yield Asn-α2AP and have named it antiplasmin-cleaving enzyme (APCE). APCE is similar in primary structure and catalytic properties to membrane-bound fibroblast activation protein/seprase for which a physiologic substrate has not been clearly defined. We found that Asn-α2AP becomes cross-linked to fibrin by activated factor XIII approximately 13 times faster than native Met-α2AP during clot formation and that clot lysis rates are slowed in direct proportion to the ratio of Asn-α2AP to Met-α2AP in human plasma. We conclude that APCE cleaves Met-α2AP to the derivative Asn-α2AP, which is more efficiently incorporated into fibrin and consequently makes it strikingly resistant to plasmin digestion. APCE may represent a new target for pharmacologic inhibition, since less generation and incorporation of Asn-α2AP could result in a more rapid removal of fibrin by plasmin during atherogenesis, thrombosis, and inflammatory states.

Reductions in plasmin inhibitor and fibrinogen predict the improved fibrin clot lysis 6 months after obesity surgery

2020 ◽  
Vol 10 (6) ◽  
Author(s):  
Nadja Bødker Pedersen ◽  
Charlotte R. Stolberg ◽  
Lene H. Mundbjerg ◽  
Claus B. Juhl ◽  
Bibi Gram ◽  
...  
Keyword(s):  
Obesity Surgery ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Plasmin Inhibitor

Effects of α2-Plasmin Inhibitor on Fibrin Clot Lysis. Its Comparison with α2-Macroglobulin

1978 ◽  
Vol 39 (01) ◽  
pp. 022-031 ◽  
Author(s):  
Nobuo Aoki ◽  
Masaaki Moroi ◽  
Kazuko Tachiya
Keyword(s):  
Binding Site ◽  
Plasminogen Activator ◽  
Fibrinolytic Activity ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Weakly Bound ◽  
Efficient Inhibitor ◽  
Α2 Macroglobulin ◽  
Plasmin Inhibitors ◽  
Plasmin Inhibitor

SummaryThe major plasmin inhibitors namely α2-plasmin inhibitor and α2-macroglobulin were compared for their effects on lysis of fibrin clot.Plasmin fibrinolytic activity was immediately inhibited by α2-plasmin inhibitor, whereas α2-macroglobulin inhibited plasmin progressively. Urokinase(plasminogen activator)-induced clot lysis was inhibited efficiently by α2-plasmin inhibitor present in the clot. Inhibition of urokinase-induced clot lysis by α2-macroglobulin was weak and the molar concentration necessary for α2-macroglobulin to achieve the same degree of inhibition as that achieved with α2-plasmin inhibitor was about 10 times higher than that of α2-plasmin inhibitor.Binding of Lys-plasminogen to fibrin was inhibited by α2-plasmin inhibitor but not by α2-macroglobulin. Molar concentrations of α2-plasmin inhibitor which were effective in inhibiting the binding were 30 times less than that of 6-aminohexanoic acid. α2-Plasmin inhibitor was found to interact with Lys-plasminogen to form a weakly-bound complex which is dissociable in the presence of 6-aminohexanoic acid, suggesting that inhibition of binding of Lys-plasminogen to fibrin by α2-plasmin inhibitor may be due to interaction of α2-plasmin inhibitor with a specific site of the plasminogen molecule and that the site may be 6-aminohexanoic acid-binding site.It is suggested that α2-plasmin inhibitor is more reactive and efficient inhibitor of fibrinolysis than α2-macroglobulin.

STRUCTURE OF HUMAN α2-PLASMIN INHIBITOR DEDUCED FROM THAT OF cDNA

1987 ◽  
Author(s):  
Y Sumi ◽  
Y Nakamura ◽  
M Sakai ◽  
M Muramatsu ◽  
N Aoki
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Stop Codon ◽  
Amino Acid Sequences ◽  
The Other ◽  
Terminal Sequence ◽  
Amino Terminal ◽  
Carboxyl Terminal ◽  
Plasmin Inhibitor

The complete amino acid sequence of α2-plasmin inhibitor (α2PI) was determined by cDNA cloning. A Agt 10 cDNA library was prepared from poly(A)+mRNA isolated from cultured human liver cells. The labeled oligonucleotides, corresponding to the reported partial amino acid sequences of α2PI, were used as probes to screen the library. One of the positive clones was subcloned into plasmid pUC8. A 2.2 kilobase cDNA clone thus isolated contains a region coding for a portion of a leader sequence, the mature protein, a stop codon (TGA), a 3' noncoding region (733 nucleotides), and a poly(A)tail (37 nucleotides). The amino acid sequence deduced from the cDNA is composed of 452 amino acids starting with an amino-terminal sequence of Asn-Gln-Glu-Gln and ending with a carboxyl-terminal sequence of Gly-Ser-Pro-Lys. The sequence shows approximately 30% homology with those of other plasma serine protease inhibitors. However, α2PI extends 50-52 amino acids beyond the carboxyl-terminal ends of the other inhibitors. This 50-52 carboxyl-terminal amino acid sequence is therefore specific to α2PI, and contains the sequence that is exactly the same as that of the peptide containing the plasminogen binding site. There are three lysine residues possibly involved in the binding to plasminogen in this region. From the homology with the other inhibitors, the inhibitor's reactive-site peptide bond was suggested to be Met-Ser and the same as that of ai-antitrypsin. The Met residue is located at the 362 position from the amino-terminal end.

The Roles of α2-Antiplasmin and Plasminogen Activator Inhibitor 1 (PAI-1) in the Inhibition of Clot Lysis

1993 ◽  
Vol 70 (02) ◽  
pp. 301-306 ◽  
Author(s):  
Linda A Robbie ◽  
Nuala A Booth ◽  
Alison M Croll ◽  
Bruce Bennett
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Dependent Inhibition ◽  
Activator Inhibitor ◽  
Pai 1

SummaryThe relative importance of the two major inhibitors of fibrinolysis, α2-antiplasmin (α2-AP) and plasminogen activator inhibitor (PAI-1), were investigated using a simple microtitre plate system to study fibrin clot lysis in vitro. Cross-linked fibrin clots contained plasminogen and tissue plasminogen activator (t-PA) at concentrations close to physiological. Purified α2-AP and PAI-1 caused dose-dependent inhibition. All the inhibition due to normal plasma, either platelet-rich or poor, was neutralised only by antibodies to α2-AP. Isolated platelets, at a final concentration similar to that in blood, 2.5 × 108/ml, markedly inhibited clot lysis. This inhibition was neutralised only by antibodies to PAI-1. At the normal circulating ratio of plasma to platelets, α2-AP was the dominant inhibitor. When the platelet:plasma ratio was raised some 20-fold, platelet PAI-1 provided a significant contribution. High local concentrations of PAI-1 do occur in thrombi in vivo, indicating a role for PAI-1, complementary to that of α2-AP, in such situations.

Inhibition of the Activities of α2-Plasmin inhibitor (PI) and CI inhibitor (CI-Inh) by the Synthetic Fibrinolytic Agent, 3-Hydroxypropyl Flufenamide (Flu-HPA)

1979 ◽  
Author(s):  
L Miles ◽  
J Burnier ◽  
M Verlander ◽  
M Goodman ◽  
A Kleiss ◽  
...  
Keyword(s):  
Plasminogen Activators ◽  
Inhibitory Effect ◽  
Mechanisms Of Action ◽  
Flufenamic Acid ◽  
Clot Lysis ◽  
Factor Xiia ◽  
Dependent Inhibition ◽  
Normal Human ◽  
Plasmin Inhibitor

Flu-HPA is one of a series of flufenamic acid derivations that enhances plasminogen-dependent clot lysis in vitro. Studies of possible mechanisms of action of Flu-HPA were undertaken. The influence of Flu-HPA on the inhibition of purified plasmin by purified PI was studied. PI activity was assessed by its inhibition of the clevage of the tripeptide S-2251 (H-D-Val-Leu-Lys-pNA) by plasmin. Flu-HPA was dissolved in DMF or in methonol and preincubated with PI before addition of plasmin. At Flu-HPA concentrations greater than 1mM and up to 60mM, the inhibitory activity of PI was totally lost. The inhibitory effect of normal human plasma on plasmin was also completely abolished at concentrations of Flu-HPA between 2.5 and 40mM. The effect of Flu-HPA on the inhibition of purified plasma kallikrein by purified CI-Inh was also studied. CI-Inh activity was measured by its inhibition of cleavage of the tripeptide Bz-Pro-Phe-Arg-pNA by kallikrein. When Flu-HPA, dissolved in DMF or in methonol, was preincubated with CI-Inh, a concentration dependent inhibition of CI-Inh activity was observed. CI-Inh activity was abolished by concentrations of Flu-HPA greater than 1mM. Flu-HPA also inhibited the activity of CI-Inh on purified Factor XIIa. These observations suggest that this flufenamic acid derivative may enhance fibrinolysis not only by inhibiting PI activity but also by decreasing the inactivation of plasminogen activators by CI-Inh.

Sign in / Sign up

Export Citation Format

Share Document